Conventionally, there is an image forming apparatus of an electrophotographic manner. This image forming apparatus, generally, charges a photosensitive drum uniformly to initialize, and forms an electrostatic latent image on this photosensitive drum by optical writing. Then, a toner image is generated from the electrostatic latent image, and the toner image is directly or indirectly transferred to a transfer material such as a sheet and affixed by a fixing unit.
For a developing device as above, since toner is consumed as the electrostatic latent image is developed to the toner image, the toner is supplied to the developing device continuously in order to maintain an adequate development performance. In many cases, a toner cartridge of an attachment-and-detachment exchange type is used for the toner supply.
As the toner supply from the toner cartridge is discharged, the toner in the toner cartridge is used up in due time, then the toner cartridge becomes empty. The toner cartridge which becomes empty would need to be exchanged for new one in order to continue operating.
In the exchange of the toner cartridge, the toner cartridge is provided with a toner residual quantity detection sensor for example, when the toner residual quantity detection sensor detects out of toner in the toner cartridge, an exchange of the toner cartridge request is relayed to a user by a display device or a warning light of operation panel.
Moreover, with respect to this informing of the exchange time of the toner cartridge, a known technology of a dot counter may be used in some cases. The dot counter calculates the amount of toner consumption based on the exposure time of a recording head which has applied an optical writing to a photoreceptor (=area of the light illuminated to the photoreceptor), utilizing that the toner moves to the part where the optical writing is applied to the photoreceptor and forms an image, and the dot counter calculates the out of toner in the toner cartridge. According to this method, it is also possible to omit the toner residual quantity detection sensor.
Then, when knowledge of the exchange of the toner cartridge is known, it is a common practice for the user to stop the operation of the image forming apparatus, exchange the old and new toner cartridge, turns on operation switch of the image forming apparatus, and resume an image forming process.
In the case where the user does not store the toner cartridge for exchanging an old toner cartridge for a new toner cartridge, the old and new toner cartridge cannot be exchanged immediately. In such case, it is not possible to use the image forming apparatus, and a user's operativity may be reduced.
In both the cases of once stopping the operation of the image forming apparatus as described above and the case in which the image forming apparatus cannot be used because the new toner cartridge is not stored, it remains that the user's operativity is reduced.
Unexamined Japanese Patent Application KOKAI Publications No. 2003-029518 and No. 2005-241868 disclose an image forming apparatus. The image forming apparatus comprises a configuration which supplies the toner to the reserve tank from the toner cartridge capable of fitting to and removing from the main body of the image forming apparatus, and conveys the toner from the reserve tank to the developing equipment, so that exchange of the toner cartridge may be possible without stopping the operation of the main body of the image forming apparatus.
Moreover, as an example of one having the reserve tank, there is an image forming apparatus proposed in Unexamined Japanese Patent Application KOKAI Publication No. 2006-113137. This image forming apparatus is considered a downsizing of entire apparatus, can be applied to a color image forming apparatus of a tandem type, and proposes a developer conveying apparatus which can move easily between an image forming operating position where a developer is conveyed to the developing equipment and a maintenance work position where an extraction work of the developing equipment can be done.
According to Unexamined Japanese Patent Application KOKAI Publications No. 2003-029518 and No. 2005-241868 described above, the toner cartridge and the reserve tank are located in the position separated from the developing equipment, in the color image forming apparatus having a developing device of a rotary type and the color image forming apparatus of a tandem type.
In such configuration in which the reserve tank is provided between the toner cartridge and a development section, there is a problem to be solved that a toner conveying apparatus becomes large-sized since the reserve tank and developing equipment are located in separate positions.
Further, the distance of toner conveyance increases as the toner conveying apparatus is disposed between, the reserve tank and the developing equipment, there is a problem to secure a quick responsiveness of the toner supply into the development section.
On the other hand, the technique disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2006-113137 intends to downsize the developer conveying apparatus. However, there is no disclosure that it is possible to exchange the toner cartridge without stopping operation of the main body of the image forming apparatus. Therefore, even if the developer conveying apparatus is downsized, there remains the problem to be solved.